"Age of Mythology" is a computer game that requires you to build a civilisation and an accompanying army from the ground up. You must maintain this civilisation and help it prosper through the ages, completing various objectives along the way. Although a population limit in the game prevents you from expanding the people who live in your civilisation as you see fit, you can remove the population limit by building a specific building.
Click on one of your "Explorers." These types of units are likely wandering your existing civilisation and will be either building new structures or mining for resources.
Click the "Town Center" button in the toolbar for your explorer. Every town centre you build removes the existing population limit, allowing you to build more structures and add more troops and other units to your civilisation.
Click inside your civilisation at the exact point where you want your town centre to go. Your explorer will immediately begin to build the town centre. When it is complete, your population limit will increase.
Place each new town centre in a protected area on your map. If an enemy army attacks and destroys the town centre, your population limit will decrease accordingly.